Numerical Prediction of Thermo-Acoustic Instability in Rijke Tube Using Non-Linear Model for Heat Source

초록

The thermal system like a combustion chamber is believed to experience a significant instability problem with vibration in case that the thermal energy or the acoustic energy are transformed into a different form through a relevant path. This study deals with a numerically- predicted, thermo-acoustic instability in a Rijke tube by using a non-linear model for a heat source. The unstable, thermo-acoustic characteristics are analyzed for heat locations, heating powers, and flow-rates, and their results are compared with experimental ones. The heating part where the energy transformation occurs actively is modeled after simulating two-dimensional cylinder case with constant surface temperature, and a nonlinear model that accounts for the transfer function of magnitude- and phasecharacteristics is properly implemented so as to be dependent on the pulsation strength in the tube. The heat source model is observed to result in equivalent thermo-acoustic instabilities in the Rijke tube except low flow-rate cases in which the natural convection is dominant.